Implantable medical devices are in common use for treating a variety of vascular and other medical conditions. Where possible, these devices are advantageously introduced into the patient by an endoluminal procedure form a remote percutaneous entry point, such as from the femoral artery or the jugular vein. Introducer assemblies are used for this purpose, which typically include a delivery sheath or catheter through which the medical device is carried, often on a suitable device carrier. The Seldinger technique is commonly used.
It is important that the implantable medical device is securely held to the introducer assembly in order to ensure that it is properly positioned at the desired treatment site and only then released in controlled manner and at the desired time. In many instances the implantable medical device is preloaded and fixed to the carrier at the stage of assembly of the apparatus, in which case there is rarely any risk of the medical device being improperly held or releasing without intention. On the other hand, in some instances the medical device is chosen in situ, that is in the course of a medical procedure, in which case it is up to the medical practitioner to fit the medical device to the introducer. A typical example are embolization coils, where the medical practitioner will choose the length and/or size of coil in dependence upon the state of the vessel and degree of occlusion required as determined in the course of the medical procedure. It is common to need to fit a plurality of coils, typically of different size, during the medical procedure, until the required degree of occlusion has been achieved. There is a risk in such situations that the medical device will be improperly attached to the carrier and as a result that the device will be incorrectly deployed in the patient's vessel. This can occur in particular when a fixed size carrier or sheath is used during the procedure.
Examples of prior art medical implant delivery devices may be found in U.S. Pat. No. 5,601,600, U.S. Pat. No. 6,989,020, U.S. Pat. No. 6,277,125, U.S. Pat. No. 5,133,727, U.S. Pat. No. 3,827,437, WO-2006/082100, WO-2010/130297, DE-2,945,237, DE-2,850,156, DE-3,407,708, DE-4,115,136 and German Utility Model DE-U-20/2010,000,786.